1. Field of the Invention
The present invention relates to an information recording and reproducing apparatus in which a fine recording pit is formed on a surface of a disk, utilizing a tunnel current generated between an edge of a tip and the surface of the disk. In addition, the invention relates to an information recording and reproducing slider to be used for such an apparatus, and also relates to a method for manufacturing the slider.
2. Description of the Related Art
Conventionally, an STM (Scanning Tunneling Microscope) has been known as an apparatus for observing the surface of an object on an atomic scale. According to the STM, concavities and convexities of the surface of the object can be measured by bringing a fine probe extremely close to the surface of the object, and then detecting a tunnel current which is generated between the fine probe and the surface of the object.
Such an STM has conventionally been used not only as a means for observing the surface of the object, but also as a means for operating atoms and/or molecules on the surface of the object. By using a finely moving function of the STM and supplying a strong electric field via the probe, the atoms and/or molecules on the surface of the object can be removed or fixed. As a result, a desired structure can be constructed on an atomic scale. Recently, there has arisen an attempt to record information by forming concavities and convexities on a surface of a substrate (disk) on an atomic scale, using the STM.
As shown in FIG. 4, the STM generally includes a cylindrical actuator 4, and a tip (probe) 5 arranged on an edge portion of the actuator 4. On the outer surface of the actuator 4, piezoelectric elements 1, 2, and 3 are arranged. When the tip 5 is brought close to the substrate surface, a tunnel current is generated corresponding to a concavity or convexity on the surface to which the tip 5 is brought close. Therefore, by detecting the tunnel current, the concavity or convexity can be measured. In addition, a crater-shaped fine pit can be formed on the substrate surface by applying a strong current to the tip 5 of the STM. This crater-shaped fine pit can be used as a recording pit to record information to the substrate. There has been proposed another method to record information to the substrate by changing a magnetic property or a dielectric constant of a substrate material. These methods have been described in detail in "NIKKEI MICRODEVICES", July, 1991, p. 89.
As above mentioned, the recording pit can be formed on the disk surface on an atomic scale so as to record and reproduce the information, using the STM. However, an information recording and reproducing apparatus using such an STM is disadvantageously enlarged in size, and the cost of the apparatus becomes expensive. Since the conventional STM shown in FIG. 4 uses a bulk type of piezoelectric element as a driving element thereof, the resulting apparatus is inevitably enlarged in size and the cost thereof becomes expensive.
To overcome the above discussed problems, there has been proposed an information recording and reproducing apparatus utilizing the principles of the STM, such as described in Japanese Laid-Open Patent Publication Nos. 4-157644 and 4-206536. In such an information recording and reproducing apparatus, a structure in which a plurality of tips are arranged is attached to a piezoelectric element, and the plurality of tips are subsequently supplied with a voltage from the piezoelectric element, thereby recording information to the disk and reproducing the information from the disk.
Such an information recording and reproducing apparatus can be made small-sized, but has a disadvantage that the tips and the piezoelectric element for applying a voltage to the tips become complicated in structure. In addition, a mechanism for positioning the tips at a desired track on the disk inevitably becomes complicated.
In all of the above discussed conventional apparatus, the scanning speed of the tip is determined by the driving speed of the piezoelectric element, which limits the improvement of the scanning speed. Therefore, even if the STM is used in order to remarkably increase the recording density of the disk, the resulting apparatus still has problems in that the signal cannot be transmitted to the disk at a higher speed and the recording density of the disk cannot be improved sufficiently.